Why are in-game purchases a problem for young people?

All in-game purchases on the new Star Wars game have been temporarily stopped after complaints. Electronic Arts (EA), which makes the game, has received a lot of criticism from fans and politicians around the world for the way in which people can buy or earn characters in 'Star Wars Battlefront II'. In America, the Entertainment Software Ratings Board (ESRB) which sorts out things like age ratings on video games, has said it does not consider loot boxes to be gambling, as: “the player is always guaranteed to receive in-game content (even if the player unfortunately receives something they don't want).”